surface merge conflicts in pr status (#5999)

pkg/cmd/pr/status/fixtures/prStatusChecks.json

@@ -7,7 +7,7 @@
       }
     },
     "viewerCreated": {
-      "totalCount": 3,
+      "totalCount": 4,
       "edges": [
         {
           "node": {
@@ -16,6 +16,7 @@
             "state": "OPEN",
             "url": "https://github.com/cli/cli/pull/8",
             "headRefName": "strawberries",
+            "mergeable": "UNKNOWN",
             "reviewDecision": "CHANGES_REQUESTED",
             "statusCheckRollup": {
               "nodes": [
@@ -98,6 +99,7 @@
             "state": "OPEN",
             "url": "https://github.com/cli/cli/pull/6",
             "headRefName": "avo",
+            "mergeable": "MERGEABLE",
             "reviewDecision": "REVIEW_REQUIRED",
             "statusCheckRollup": {
               "nodes": [
@@ -125,6 +127,33 @@
               ]
             }
           }
+        },
+        {
+          "node": {
+            "number": 5,
+            "title": "Why can't berries get along?",
+            "state": "OPEN",
+            "url": "https://github.com/cli/cli/pull/5",
+            "headRefName": "strawberries",
+            "mergeable": "CONFLICTING",
+            "statusCheckRollup": {
+              "nodes": [
+                {
+                  "commit": {
+                    "statusCheckRollup": {
+                      "contexts": {
+                        "nodes": [
+                          {
+                            "state": "SUCCESS"
+                          }
+                        ]
+                      }
+                    }
+                  }
+                }
+              ]
+            }
+          }
         }
       ]
     },

pkg/cmd/pr/status/http.go

@@ -12,10 +12,11 @@ import (
 )
 
 type requestOptions struct {
-	CurrentPR int
-	HeadRef   string
-	Username  string
-	Fields    []string
+	CurrentPR      int
+	HeadRef        string
+	Username       string
+	Fields         []string
+	ConflictStatus bool
 }
 
 type pullRequestsPayload struct {
@@ -56,7 +57,7 @@ func pullRequestStatus(httpClient *http.Client, repo ghrepo.Interface, options r
 		fragments = fmt.Sprintf("fragment pr on PullRequest{%s}fragment prWithReviews on PullRequest{...pr}", gr)
 	} else {
 		var err error
-		fragments, err = pullRequestFragment(httpClient, repo.RepoHost())
+		fragments, err = pullRequestFragment(repo.RepoHost(), options.ConflictStatus)
 		if err != nil {
 			return nil, err
 		}
@@ -186,12 +187,16 @@ func pullRequestStatus(httpClient *http.Client, repo ghrepo.Interface, options r
 	return &payload, nil
 }
 
-func pullRequestFragment(httpClient *http.Client, hostname string) (string, error) {
+func pullRequestFragment(hostname string, conflictStatus bool) (string, error) {
 	fields := []string{
 		"number", "title", "state", "url", "isDraft", "isCrossRepository",
 		"headRefName", "headRepositoryOwner", "mergeStateStatus",
 		"statusCheckRollup", "requiresStrictStatusChecks",
 	}
+
+	if conflictStatus {
+		fields = append(fields, "mergeable")
+	}
 	reviewFields := []string{"reviewDecision", "latestReviews"}
 	fragments := fmt.Sprintf(`
 	fragment pr on PullRequest {%s}

pkg/cmd/pr/status/status.go

@@ -30,6 +30,7 @@ type StatusOptions struct {
 
 	HasRepoOverride bool
 	Exporter        cmdutil.Exporter
+	ConflictStatus  bool
 }
 
 func NewCmdStatus(f *cmdutil.Factory, runF func(*StatusOptions) error) *cobra.Command {
@@ -57,6 +58,7 @@ func NewCmdStatus(f *cmdutil.Factory, runF func(*StatusOptions) error) *cobra.Co
 		},
 	}
 
+	cmd.Flags().BoolVarP(&opts.ConflictStatus, "conflict-status", "c", false, "Display the merge conflict status of each pull request")
 	cmdutil.AddJSONFlags(cmd, &opts.Exporter, api.PullRequestFields)
 
 	return cmd
@@ -91,13 +93,15 @@ func statusRun(opts *StatusOptions) error {
 	}
 
 	options := requestOptions{
-		Username:  "@me",
-		CurrentPR: currentPRNumber,
-		HeadRef:   currentPRHeadRef,
+		Username:       "@me",
+		CurrentPR:      currentPRNumber,
+		HeadRef:        currentPRHeadRef,
+		ConflictStatus: opts.ConflictStatus,
 	}
 	if opts.Exporter != nil {
 		options.Fields = opts.Exporter.Fields()
 	}
+
 	prPayload, err := pullRequestStatus(httpClient, baseRepo, options)
 	if err != nil {
 		return err
@@ -264,6 +268,17 @@ func printPrs(io *iostreams.IOStreams, totalCount int, prs ...api.PullRequest) {
 				fmt.Fprint(w, cs.Green(fmt.Sprintf("✓ %s Approved", s)))
 			}
 
+			if pr.Mergeable == "MERGEABLE" {
+				// prefer "No merge conflicts" to "Mergeable" as there is more to mergeability
+				// than the git status. Missing or failing required checks prevent merging
+				// even though a PR is technically mergeable, which is often a source of confusion.
+				fmt.Fprintf(w, " %s", cs.Green("✓ No merge conflicts"))
+			} else if pr.Mergeable == "CONFLICTING" {
+				fmt.Fprintf(w, " %s", cs.Red("× Merge conflicts"))
+			} else if pr.Mergeable == "UNKNOWN" {
+				fmt.Fprintf(w, " %s", cs.Yellow("! Merge conflict status unknown"))
+			}
+
 			if pr.BaseRef.BranchProtectionRule.RequiresStrictStatusChecks {
 				switch pr.MergeStateStatus {
 				case "BEHIND":

pkg/cmd/pr/status/status_test.go

@@ -113,9 +113,10 @@ func TestPRStatus_reviewsAndChecks(t *testing.T) {
 	}
 
 	expected := []string{
-		"✓ Checks passing + Changes requested",
+		"✓ Checks passing + Changes requested ! Merge conflict status unknown",
 		"- Checks pending ✓ 2 Approved",
-		"× 1/3 checks failing - Review required",
+		"× 1/3 checks failing - Review required ✓ No merge conflicts",
+		"✓ Checks passing × Merge conflicts",
 	}
 
 	for _, line := range expected {